Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <c4b34414-cc12-0d0f-49a1-f73c9d17611e@linux.intel.com>
Date:   Fri, 10 Jun 2022 16:31:16 +0300
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Firefox/91.0 Thunderbird/91.9.0
Subject: Re: [PATCH] i2c: designware: Use standard optional ref clock
 implementation
Content-Language: en-US
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc:     Mika Westerberg <mika.westerberg@linux.intel.com>,
        Jan Dabros <jsd@semihalf.com>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Phil Edworthy <phil.edworthy@renesas.com>,
        Gareth Williams <gareth.williams.jx@renesas.com>,
        Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
        Serge Semin <fancer.lancer@gmail.com>,
        Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
        linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220610074233.9748-1-Sergey.Semin@baikalelectronics.ru>
 <YqMovttAaGBw796k@smile.fi.intel.com>
From:   Jarkko Nikula <jarkko.nikula@linux.intel.com>
In-Reply-To: <YqMovttAaGBw796k@smile.fi.intel.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 6/10/22 14:19, Andy Shevchenko wrote:
> On Fri, Jun 10, 2022 at 10:42:33AM +0300, Serge Semin wrote:
>> Even though the DW I2C controller reference clock source is requested by
>> the method devm_clk_get() with non-optional clock requirement the way the
>> clock handler is used afterwards has a pure optional clock semantic
>> (though in some circumstances we can get a warning about the clock missing
>> printed in the system console). There is no point in reimplementing that
>> functionality seeing the kernel clock framework already supports the
>> optional interface from scratch. Thus let's convert the platform driver to
>> using it.
>>
>> Note by providing this commit we get to fix two problems. The first one
>> was introduced in commit c62ebb3d5f0d ("i2c: designware: Add support for
>> an interface clock"). It causes not having the interface clock (pclk)
>> enabled/disabled in case if the reference clock isn't provided. The second
>> problem was first introduced in commit b33af11de236 ("i2c: designware: Do
>> not require clock when SSCN and FFCN are provided"). Since that
>> modification the deferred probe procedure has been unsupported in case if
>> the interface clock isn't ready.
> 
> Makes sense,
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>